DNA oligonucleotides (oligodeoxyribonucleotides, oligodeoxyribonucleic acids, ODNs, oligonucleotides) are short DNA-based synthetic polymers that can be synthesised and highly purified in significant quantities. The sequence of monomers (deoxyribonucleotides) in oligonucleotides is termed as the primary structure of DNA. The secondary structure of a nucleic acid molecule refers to the base-pairing interactions within a single molecule or set of interacting molecules. The tertiary structure of DNA is determined as its spatial organization (IUPAC). ODNs in physiologically relevant aqueous solutions are considered to be random-coiled single-stranded or in the tertiary structure of double-stranded DNA helix.
The double helix is the dominant tertiary structure for biological DNA that can be in one of three DNA conformations and are believed to be found in nature, A-DNA, B-DNA, and Z-DNA. The B-form described by Watson and Crick is believed to predominate in cells (Richmond T. J., et al. (2003) Nature 423 (6936): 145-150). However, several types of nucleic acid structures can be observed that are different from random or classical double-stranded helix forms. Among them are triplexes, quadruplexes and other nucleic acid structures (Soyfer, V. N and Potaman V. N. (1995) Triple-Helical Nucleic Acids. Springer Ver., New York, 360 pp; Burge S., et al. (2006) Nucleic Acids Research, 34, 19, 5402-5415).
Recently, it has been found that particular G-rich DNA sequences are capable of forming stable four-stranded structures known as G-quadruplexes (G-quartets) (Burge S., et al. (2006) Nucleic Acids Research, 34, 19, 5402-5415; Huppert, J. L. (2008) 37(7):1375-84; Neidle and Balasubramanian (2006) Quadruplex Nucleic Acids, RSC Publishing, Cambridge, UK, 302 pp). G-quartets arise from the association of four adjacent G-bases assembled into a cyclic conformation. These structures are stabilized by von Hoogsteen hydrogen bonding and by base stacking interactions (Skogen M., et al., (2006) BMC Neuroscience 7:65). G-quadruplexes have been shown to be relevant in biological processes as being important components of human telomeres, and playing a role in the regulation of transcription as well as translation (Patel et al., (2007) Nucleic Acids Res. 35(22):7429-55; Oganesian L, and Bryan T M (2007) Bioessays 29(2):155-65; Qin and Hurley (2008) Biochimie., 90 (8):1149-71; Siddiqui-Jain et al., (2002) Proc Natl Acad Sci USA. (2002) 3; 99(18):11593-8; Kumari et al., (2007) Nat Chem Biol. 2007, 3(4):218-21).
Parekh-Olmedo et al., ((2004) J Mol Neurosci. 24(2):257-67) showed that certain groups of ODNs can inhibit pathological protein aggregation in Huntington's disease. One of these groups was the G-rich oligonucleotides (GROs). G-quartet formation has also been implicated in the non-antisense antiproliferative effects of GROs. In several cases, the biological effects of oligonucleotides designed as antisense agents were found to be unrelated to inhibition of target protein expression, but instead were associated with the formation of G-quartet structures (Burgess et al., (1995) Proc. Natl. Acad. Sci. USA, 92, 4051-4055; Anselmet, A., et al., (2002) FEBS Lett., 510, 175-180; Benimetskaya, L., et al., (1997) Nucleic Acids Res., 25, 2648-2656; Saijo, Y et al., (1997) Jpn J. Cancer Res., 88, 26-33).
The molecular mechanisms of GRO action are not fully known. One of them appears to be related to the ability of oligonucleotides to bind to nucleolin (Bates, P. J., et al. (1999) J. Biol. Chem., 274, 26369-26377). Binding of nucleolin to other G-quartet-forming sequences such as telomeric DNA, immunoglobulin switch regions and ribosomal genes has also been reported (Dempsey, L. A., et al., (1999) J. Biol. Chem., 274, 1066-1071; Hanakahi, L. A. et al., (1999) J. Biol. Chem., 274, 15908-15912; Ishikawa, F. et al., (1999) Mol. Cell. Biol. 13, 4301-4310; Dickinson, L. A. and Kohwi-Shigematsu, T. (1995) Mol. Cell. Biol., 15, 456-465).
Treatment of tumour cells with G-rich oligonucleotides was found to inhibit cell cycle progression by specifically interfering with DNA replication, whereas GRO-treated normal skin cells exhibited minimal perturbation of the cell cycle (Xu X., et al., (2001) J. Biol. Chem. 276, 43221-43230). Further, Antisoma plc, developed G-quadruplex based AS-1411 that is the first oligodeoxyribonucleotide aptamer that reached clinical trials for the potential treatment of cancers, including acute myelogenous leukemia (AML) (Ireson CR and Kelland L R, (2006) Mol Cancer Ther. 5 (12):2957-62; Mongelard F. and Bouvet P., (2006) Curr Opin Mol Ther. 12(1): 107-14).
G-rich oligonucleotides can form a variety of possible quadruplex structures, depending on its thermodynamic and kinetic characteristics. Quadruplexes can be formed by one, two or four molecules of oligonucleotides, which are referred to as monomer, dimer and tetramer structures, respectively. (Dapic V., et al., (2003) Nucleic Acids Research 31 (8): 2097-2107).
Circular dichroism (CD) spectroscopy is commonly used to investigate the structure and conformation of nucleic acids (Baase and Johnson Jr. (1979) Nucleic Acids Res., 6(2): 797-814; Giraldo R. et al., (1994) Proc. Natl. Acad. Sci. USA 91: 7658-7662; Hardin C. C. et al., (1991) Biochemistry 30:4460-44721992, Hardin C. C. et al., (1992) Biochemistry 31: 833-841; Paramasivan S, et al. (2007) Methods 43: 324-331) where circular dichroism refers to the differential absorption of left and right circularly polarized light (P. Atkins and J. de Paula (2005) Elements of Physical Chemistry, 4th ed. Oxford University Press). Various DNA quadruplex structures have distinctive circular dichroism spectra (Dapic V, et al., (2003) Nucleic Acids Research 31 (8): 2097-2107) providing the possibility to use selected structures as set of standards or references to compare with CD spectra of oligonucleotides.
Various immunostimulatory oligodeoxyribonucleotides containing unmethylated deoxyribodinucleotide CpG motifs (CpG ODNs) that mimic prokaryotic DNA have been developed and characterised by several research groups. It has been established that recognition of CpG ODN requires Toll-like receptor 9 (TLR9) interaction. Cells that express TLR9, which include plasmacytoid dendritic cells (PDCs) and B cells, produce Th1-like proinflammatory cytokines, interferons, and chemokines in response to CpG ODNs. Several classes of CpG ODNs are described up to date as A-, B-, C-, D- and P-class CpG ODNs (Krieg A., 2002 and 2006), however, they all have been classified based on the primary structure (nucleotide sequence) of the oligonucleotides.
In recent years, there has been tremendous progress delineating the specific components of the immune system that contribute to various aspects of normal immunity and specific disease states. This has introduced the possibility to treat diseases with immunomodulating substances as protein therapeutics, including monoclonal antibodies and cytokines, which became mainstream treatments in a number of clinical settings.
Imbalances in the cytokine cascade can help the initiation and propagation of the immune driven inflammation. In several inflammatory diseases, including rheumatoid arthritis and inflammatory bowel disease, the proinflammatory cytokine TNF-α has been shown to play a central role in inflammatory reactions and has proven to be an especially attractive target for biological agents. Immunomodulatory cytokines considered of significance in the treatment of infectious diseases, malignancies and autoimmune diseases including interferon type I (IFN-α and IFN-β), IFN-γ and IL-10.
Interferons (IFNs) are cytokines that may be released in response to viruses, bacteria, parasites and tumor cells. Interferons possess immunoregulatory, antiviral and anti-cancer properties. They have been used to successfully treat a number of chronic inflammatory disorders including multiple sclerosis (Paolicelli, D et al., (2009) Targets & Therapy; 3, 369-76), chronic viral hepatitis (Hoofnagel J H and Seeff L B, (2006) N. Eng. J. Med., 355: 2444-51; Chevaliez S and Pawlotsky J M, (2009) Handbook of Experimental Pharmacology, Antiviral Strategies, 189: 203-41) and also in neoplastic diseases (Gill P S et al., (1995) N. Eng. J. Med., 332:1744-8). There are two main classes of IFNs: Type I IFNs (α,β,ε,o,κ) are central in the host defense against pathogens such as viruses whereas type II IFN (γ) mainly contributes to the T-cell-mediated regulation of the immune responses.
IFN-α is produced by the cells of the immune system in response to the presence of a foreign antigen, inducing cell activation of macrophages and natural killer cells and enhancing antigen presentation. There are 13 subtypes of IFN-α, whereby the two subtypes IFN-α2a and IFN-α2b have been used therapeutically with similar results in hepatitis C (Welzel T M et al., (2009) Hepatology, 49: 1847-58) and renal carcinoma (Coppin C et al., (2008) The Cochrane Collaboration, Targeted therapy for advanced renal cell carcinoma, 1-38). The side effects of recombinant IFN-α can, however, be significant with up to 68% of patients presenting with psychiatric symptoms, such as depression, irritability, and insomnia.
IFN-β is produced mainly in fibroblasts and plasmacytoid dendritic cells and has 30% nucleic acid homology to IFN-α and sharing similar antiviral activity. Clinically, it has been used in the treatment of MS because of its additional anti-inflammatory effect (Durelli L et al., (2009) Ann Neurol, 65: 499-509). Currently, recombinant IFN-β is used as a first-line treatment for relapsing-remitting form of the MS disease. Common adverse events from the recombinant IFN-β are depression, flu-like symptoms, and increase of liver enzyme levels. In addition, treatment results in the induction of anti-IFN-β neutralizing antibodies (NAbs) in some patients resulting in a lost effect of treatment (Soelberg Sorensen Petal., (2003) Lancet, Vol. 362: 1184-91; Soelberg Sorensen P et. al., (2006) Neurology, 67: 1681-3). IFN-β was also used successfully as therapy in chronic inflammatory diseases as ulcerative colitis (Musch E et al., (2002) Aliment Pharmacol Ther, 3: 581-6).
IFN-γ is produced by leukocytes to induce macrophage activation and increase oxidative burst. Defects in IFN-γ and IFN-γ receptor genes have been associated with autoimmune diseases such as rheumatoid arthritis, type1 diabetes and multiple sclerosis (Chen J and Liu X, (2009) Cellular Immunology, Vol. 254: 85-90). However, treatment of autoimmune diseases supplementing with IFN-γ was ambivalent due to its broad biological effects causing unwanted activities. Further, it is clinically used to enhance immunity in patients with chronic granulomatous disease with good efficacy. Potential side effects include fever, hypotension, and flu-like symptoms (Holland S M, (2009) Clinic Rev Allerg Immunol, 38: 3-10). It is also thought to be beneficial as treatment for brain tumor immunotherapy (Hague A et al., (2007) Neurochem Res, 32: 2203-2209).
Interleukins are a group of multifunctional cytokines that are produced by a variety of lymphoid and non-lymphoid cells of the immune system to mediate communication between the immune cells and are particularly important to promote immune responses as inflammation and in the hematopoeisis. An example of a proinflammatory classified interleukin is IL-6. Its dysregulation can contribute to the induction and maintenance of several diseases such as rheumatoid arthritis and inflammatory bowel disease (Heinrich P C et al., (2003) Biochem. J., 1374: 1-20). IL-6 has also anti-inflammatory properties by for example inhibiting TNFs (Opal S M and DePalo V A, (2000) Chest Anti-inflammatory cytokines, 117: 932-4) reflecting the challenge of using a cytokine as therapy or as target for immunotherapy. In contrast, IL-10 is classified as an anti-inflammatory cytokine and is produced by monocytes, macrophages, mast cells, T and B lymphocytes, and dendritic cells. It is believed that it can suppress the production of pro-inflammatory cytokines and plays a central role in the regulation of immune responses. It also has broad implications in the development of certain inflammatory diseases, most noticeably allergy and asthma (Hawrylowicz C M and O'Garra A, (2005) Nat Rev Immunol, 202: 1459-63; Ogawa Y et. al., (2008) Curr Mol Med, 8: 437-45). Numerous clinical studies have indicated that there is a general lack of sufficient levels of IL-10 in asthmatic patients which may contribute to a more intensive inflammation as shown by K. Tomita and colleagues who described that levels of IL-10 and IL-10 producing cells were significantly reduced in patients with severe persistent asthma when compared to mild asthma (Tomita K et al., (2002) Clin Immunol, 102: 258-66). It is also believed that corticosteroids, widely used anti-inflammatory compounds, exert their anti-inflammatory effects in part by enhancing IL-10 production (Richards D F et al., (2000) Eur J Immunol, 30: 2344-54). In corticosteroid resistant asthmatic patients, corticosteroids failed to induce IL-10 synthesis suggesting a strong link between induction of IL-10 synthesis and efficacy of corticosteroids (Hawrylowicz C M et al., (2002) J Allergy Clin Immunol, 109: 369-70). Experiments from D. Hesse and colleagues (Hesse D et al., (2010) Europ. J. Neurol., 15: 1-7) indicated that the expression of endogenous IFN-β induces the expression of IL-10 in MS and that the expression of IL-10 negatively correlates with the disease activity suggesting that IL-10 expression is associated with the dampening of the inflammatory response. Furthermore, in patients with evolved neutralizing antibodies (NAbs), IL-10 expression is reduced.
The use of cell surface antigens as therapeutic targets is another growing area of modulating the immune system. Using antibody-related therapies can have several options such as binding to a specific target molecule on the cell surface to trigger cellular mechanisms such as apoptosis or activation pathways (immunotherapy), or simply binding to a target on the cell surface for delivery of an agent to the specific cell type, e.g. cytostatic agent (immuno-chemotherapy). Immunotherapy is used in the treatment or alleviation of many immunological diseases or conditions, such as cancer, inflammatory diseases such as asthma and allergy and also autoimmune disorders such as multiple sclerosis.
WO2010/053433 A1 describes the potential of specific oligonucleotides in up-regulating the expression of certain cell surface markers or cell surface antigens such as CD20, CD23, CD69 and CD80. The pre-incubation of PBMC isolated from CLL patients significantly increased the rate of apoptosis in human B-cells mediated by a monoclonal antibody directed against CD20 (rituximab).
WO2010/053430 A1 describes the capability of specific oligonucleotides to influence the properties and behaviour of polymorphonuclear cells, in particular the recruitment and/or migration of polymorphonuclear cells to a site of inflammation, and that they through this mechanism have utility in the prevention, treatment and/or alleviation of various diseases such as ischemia.
The challenges of immunotherapy and treatment with cytokines are the occurring side effects and the observed immunogenicity of these protein therapeutics even of fully human protein drugs (Vial T and Descotes J, (1994) Drug Saf, 10: 115-20; Scott D W and De Groot A S, (2010) ANN Rheum Dis, 69: 72-76). Especially, for the treatment within IFN-α it was suggested that the efficacy of the treatment has to be increased while the toxicity should be decreased (Sarasin-Filipowicz M, (2010) Swiss Med Wkly, 140: 3-11). The usage of endogenous induced IFN-α could be more effective and tolerable. P. Sfriso and colleagues could for example show that exposure to fungi is positive for the treatment of inflammatory bowel disease (Sfriso Petal., (2010) J Leuk Biol, 87: 385-95). Fungi are a natural source of foreign DNA and proteins, inducing endogenous cytokine production. Endogenous induction of cytokines could give beneficial effects without unwanted induced activities. Another aspect is that IFN-α, for example, exists in numerous subforms, however through endogenously induced expression all subforms will be expressed in their natural way. It could be shown in corticosteroid-resistant asthma patients that IL-10 is up-regulated after IFN-α treatment and the authors suggest that the beneficial effects of IFN-α lies in the production of IL-10 (Simon H U et al., (2003) Allergy, 58: 1250-1255). IL-10 has less side effects than IFN-α and therefore could be a better treatment option. Chen and colleagues described the opposite functions of IL-10 and IFN-γ in a subform of CD4+ T-cells while they are working together in the disease management of chronic infections (Chen J and Liu X S, (2009) J Leuk Biol, 86: 1305-10). These examples demonstrate how different cytokines with different biological functions can act together to modulate the pathogenesis of a disease or to maintain the fine balance in an immune response. A more effective treatment option could be a combination of different cytokines or a way to induce different cytokines endogenously. There is clearly a need to provide methods and oligonucleotides that can induce the endogenous expression of specific cytokines.